Illuminated optical apparatus

ABSTRACT

A device may include a magnifying lens having a focal length that defines a focal plane, a light source providing visible light directed toward the focal plane, and a controller. The controller may be programmed to receive a signal indicative of the distance from the device to an object, cause the light source to emit visible light at a first brightness if the distance is at least substantially equal to the focal length of the lens, and cause the light source to emit visible light at a second brightness, dimmer than the first brightness, if the distance is not at least substantially equal to the focal length of the lens.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. provisional application Ser.No. 61/141,474, filed Dec. 30, 2008, which is hereby incorporated hereinby reference.

SUMMARY

A lighted magnifier may be programmed to give feedback to a user aboutwhether a target the user is attempting to view with the magnifier ispositioned at the magnifying lens's focal length. For example, themagnifier can illuminate a target with full brightness only when thetarget is brought to or near the focal distance of the magnifying lens,and to dim or turn off the illumination when the target is not in thevicinity of the focal distance. The magnifier thus provides bothillumination and feedback to train a user to position the objectproperly with respect to the lens.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-2 are schematic diagrams of a lighted magnifier.

FIGS. 3-5 are flow diagrams showing various embodiments of controllerprogramming for lighted magnifiers.

FIGS. 6-9 illustrate embodiments of a lighted magnifier.

DETAILED DESCRIPTION

Like a number of prior-art devices, an automatic lighted magnifier aspresently disclosed includes a magnifying lens and a light source thatshines light on the target to be viewed. But it also includes acontroller that receives a signal and gives feedback to the user basedon that signal. The signal is indicative of the distance from the deviceto an object, and the feedback is indicative of whether the distance isin the lens's range of focus. In the present context, the distance isconsidered to be in the lens's range of focus if it is within 10% of thelens's focal length (i.e., no closer than 90% of the focal length and nofurther than 110% of the focal length).

Such feedback is useful for training and the use of magnifying devicessince it lets the user know what the appropriate working distance to theobject of regard should be. The feedback can be especially useful insituations in which a user requires training in the proper workingdistance for the magnifier. While positioning a target at a distanceother than the lens's focal length will result in a blurry image, theblurriness can be subtle and difficult for some users to detect. Yeteven the slight blurriness can cause fatigue and difficulty. Theinventors realized that the magnifier could be programmed to providefeedback that is more immediately and easily detectable than mereblurriness and thereby facilitate the user's familiarization with theproper working distance.

An especially convenient form of feedback is the illumination lightlevel. The controller may be programmed to turn on the illuminationlight source (or bring it up to full power from a dimmed state) onlywhen the target is positioned in the lens's range of focus, or at ornear (i.e., at a distance at least substantially equal to) the focallength of the magnifier lens. The controller receives a signalindicative of the position of the distance from the magnifier device tothe target and controls the light source based on that signal.

The signal may include, for example, numerical data that represents thedistance, and the controller compares that measurement to a preset focallength value. The signal may include numerical data that represents adifference or a ratio (such as a percentage) between the focal lengthand the distance. The signal may include Boolean data (i.e., yes/no oron/off) indicating whether the distance is in the range of focus, or atleast substantially equal to the focal length of the lens.

The signal may be produced by a sensor. The sensor may be, for example,an infrared light source and detector that are angled and positioned onthe device such that emitted sensor light bounces off the target andinto the detector only when the target is at the lens's focal length.Thus the light source will illuminate (or brighten) automatically whenthe magnifier is correctly positioned for viewing relative to thetarget. The controller will stop (or dim) the illumination when thesignal indicates that there is no target at or near the focal distance.

The controller may be programmed to keep the illumination light sourceturned on throughout the usable range of the lens even after the targetmoves away from the exact focal length and/or its vicinity (that is, theillumination will turn on only at or near the focal length but can stayon throughout a range of distances around the exact focal distance).This “buffer” may be implemented in a variety of ways, includingtime-based and distance-based. In a time-based implementation, thecontroller may include a timer that keeps the illumination brieflyturned on even if the user drifts out of the usable range, to provideillumination continuity until the user gets back into range. A timer maybe especially useful when the signal is simply a Boolean indicator ofwhether the target distance matches the focal length. But the controllerwill still turn off (or dim) the illumination if the user does not getback into range within the timer's limit. Alternatively, in adistance-based implementation of the buffer, the sensor may be designedto report any distance that is in the range of focus, or at leastsubstantially equal to the focal length, as being equal to the focallength. The controller will then maintain the illumination even when thedistance is outside the range of focus, or unequal to the focal lengthbut still at least substantially equal to the focal length. In anotheralternative, the sensor is programmed to sample the distance as itvaries over time, and the signal produced is indicative of time-averageddistance. Excursions away from the focal length are thereby filtered outuntil they shift the average distance outside the acceptable limit.

In addition to the conventional utility of providing illumination for atarget, the present magnifiers also provide the user with positioningfeedback: with a magnifier using illumination-based feedback, the usergets the best illumination when the target is positioned at the bestdistance. The user thereby can learn to position the target at thelens's focal length.

The device may employ various forms of illuminating light, such asvisible light, ultraviolet light, or infrared light, as well ascombinations of these and other portions of the electromagneticspectrum. Visible light may be white light or may be made up of varioussub-bands of visible light, such as red, green, and/or blue light.

While the embodiments described herein use the brightness of theilluminating light as the principal medium for feedback, other feedbackmodalities are possible. For example, the light could flash when out ofrange and become steady when in range. The illuminating light could bedirected away from the lens's center of focus when out of range andtoward the center when in range. The device could emit a sound,vibration, heat, or light (such as an icon on the device) depending onwhether the target is in range. The device could emit tinted light whenout of range and white light when in range. The device could alternatebetween white light and tinted light when out of range and become steadywhite light when in range. The tint of the light can vary based onpositional error: the tint can fade as the focal length is neared andintensify as it is left; or the tint can change color, such as red whenthe distance is too close and blue when too far.

FIG. 1 shows block diagram 300 of apparatus 100 that magnifies andilluminates a target. The user views the target through lens 301 so thatthe target is illuminated by illumination source 303 when rangingcircuit 305 determines that the target is at a desired distance(typically a predetermined value and equal to the focal distance of lens301) when activated by a user through user interface 309 (such as aswitch).

Processing device 307 obtains an indication from ranging circuit 305when the target is located at the desired distance and activatesillumination source 303 in accordance with process 200.

Processing device 307 may execute computer executable instructions froma computer-readable medium, e.g., memory 311. Computer storage media mayinclude volatile and nonvolatile, removable and non-removable mediaimplemented in any method or technology for storage of information suchas computer readable instructions, data structures, program modules orother data. Computer storage media include, but is not limited to,random access memory (RAM), read only memory (ROM), electronicallyerasable programmable read only memory (EEPROM), flash memory or othermemory technology, CD-ROM, digital versatile disks (DVD) or otheroptical disk storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices, or any other medium that canbe used to store the desired information and that can be accessed byprocessing device 307.

FIG. 2 schematically shows the arrangement of an apparatus 100 thatmagnifies and illuminates target 103. The apparatus may be employed onor in spectacle frames, handheld magnifiers, magnifier stands, and thelike. The apparatus includes sensor components 105 and 107 which triggerLEDs (illumination source) 101 to illuminate reading material, or anyother object to be viewed when that object is brought to within thefocal distance of a lens (not shown).

Apparatus 100 not only provides for the light necessary for seeing, italso allows a user to know exactly where the user should be holding thereading material for the best optical focus. This capability may beimportant with low vision when dealing with higher powered lenses thatrequire shorter working distances.

Apparatus 100 operates on the premise that the object (target) is infocus at the focal point of the lens.

Apparatus 100 includes a lens system (not shown in FIG. 2 but shown inFIGS. 6-9), an illuminator, a sensor, and mounts for those components.Apparatus 100 magnifies and activates an illuminator at the focal pointof the magnifier, thus providing illumination and a positive feedback tothe user that the magnifier is being used properly.

Upon energizing the momentary power switch 111, the power controlcircuit 109 is activated. A function of power control circuit 109 is toprovide power to the rest of the circuitry of apparatus 100 and to turnoff the power when apparatus 100 is no longer being used. The powercontrol circuit 109 utilizes a timer to keep power on after themomentary power switch 111 is activated. This timer is reset by feedbackfrom range finder modulated light processing circuit 117. As long asapparatus 100 is sensing target 103, the power will stay on, and for ashort time thereafter, as determined by the timer in power controlcircuit 109. This approach saves electrical power while providingconvenience to the user.

When apparatus 100 is initialized, range finder sense timer 113 sends asignal to the modulated light driver circuit 115 triggering a series ofpulses to range finder source 105. A function of range finder sensetimer 113 is to conserve power. Range finder light source 105 does nothave to operate continuously; an intermittent test of the distance tothe target is adequate. The modulated light driver circuit 115 providesa series of pulses to the range finder light source 105; for example, asignal may be transmitted with a modulation frequency of 38 kHz in 10msec. bursts every 100 msec. These pulses have a short “on” duty cycle,thus conserving electrical power.

The ranging distance to target 103 may be determined by thetriangulation method. Both the range finder light source 105 and thefield of view of the range finder receiver 107 intersect at target 103.This intersection may be set by way of adjustment screws and calibratedat a determined distance in front of and behind the focal point of themagnifier, providing a clear image within the range of focus to theviewer. When target 103 is moved into the intersection point of rangefinder light source 105 and ranger finder receiver 107, the reflectedmodulated light becomes intense enough to trigger the output of rangefinder modulated light processing circuit 117. Range finder modulatedlight processing circuit 117 is only sensitive to the modulated lightemitted by the range finder source 105, therefore reducing interferencefrom other light sources, including illumination light source 101. Thisaction in turn starts illumination hold timer 119. Illumination holdtimer 119 keeps illumination light source 101 in the “on” state shouldtarget 101 be moved out of the intersection point for a short period oftime. The output of the illumination hold timer 119 signals theillumination light source driver 121 to turn on the “illumination lightsource 101, thus illuminating target 103.

A function of the sensor 117 is to activate (turn on) illuminationsource 101 when an object (target 103) to be viewed is at or near thefocal length of the lens system or through the range of focus of thelens. Various methods of range finding can be employed. These includebut are not limited to a triangulation method, strength of reflectedsignal method, or timing of the signal reflected back from the object(time of flight measurement). Other methods could be employed to sensethe focal distance such as utilizing an algorithm to analyze the imageas projected onto an image sensor array, a linear image sensor,interferometer, or phase shift method. The above sensing methods couldutilize infrared light, visible light, solid state laser or sound waves.

As shown in FIGS. 6-9, illumination light source 101 and range finderlight source do not typically illuminate through the lens (though theymay) but rather around the periphery of the lens.

Power conservation may be enhanced in a variety of ways. Range findersense timer 113, the short duty cycle modulated pulses provided by themodulated light driver circuit 115, and the use of momentary powerswitch 111 contribute to conserving electrical power. Apparatus 100 istypically powered by replaceable or rechargeable batteries and sobenefits from reductions in power consumption. In cases where electricalpower is provided by an external source, e.g., standard wall current, ACadapter, or wall mounted power supply, power saving techniques may beless important or desirable. The device can adjust the logic that thecontroller uses depending on the power source.

The range finder source 105 and range finder receiver 107 may include,respectively, a spectrally matched infrared (IR) LED and IR filteredphototransistor receiver with a peak sensitivity in the IR range (suchas 940 nm). IR-based range-finding offers several benefits. First, theIR LED is invisible to human eye and thus is not distracting the user.In addition the IR LED and IR filtered receiver provide an extra measureof resistance to false triggering from high ambient light conditions.Additionally, the spectrally matched pair provide excellent opticalcoupling and thus reduce the required power to operate.

A variety of light emitting devices may be used for illumination lightsource 101 based on the applicability in different applications.However, a light source providing high intensity mildly diffused whitelight is typically preferable. In cases where the user suffers fromvarious eye diseases, a colored light source may be preferable toenhance the contrast of the target image. Generally, a high efficiencyLED would be the preferred light source, but in some caseselectroluminescent or OLEDs may be a better choice based on the intendeduse.

The illuminator can be of various light frequencies, eithermonochromatic or broad spectrum as required, and may be selected tospecifically aid or enhance vision in a low vision patient. The lightcan be generated by one or more methods, including but not limited toLED, incandescent, fluorescent, OLED, or electroluminescent. Variousmethods of conveying or focusing the light can be employed including butnot limited to lens optics, fiber optics, minors, reflective surfaces orlight conductive materials. The light may or may not be diffuseddepending on its intended use.

The lens system can consist of a single lens, as in but not limited to,a hand magnifier or stand magnifier; or two lenses as in a pair ofspectacles. Several individual lenses may be used together to make up alens system. The lens system is typically fixed—i.e., not adjustable.The fixed lens system therefore has a fixed (i.e., nonadjustable) focallength, and the controller and sensor are arranged to act based on thatfocal distance. Alternatively, the device may include a lens system thatallows for adjustment (typically by allowing relative motion between thelenses), in which case the controller and sensor accommodate theadjustability.

The mount may include a spectacle frame, a stand, trial frame or a handheld device.

FIGS. 3-5 show flow diagrams for magnifier controllers. As shown in FIG.3, in step 201, circuitry of apparatus 100 is activated and the powertimer (typically located in power control circuit 109) is reset when auser depresses switch 111 as shown in FIG. 1. Step 203 determines if thepower timer has expired. If so, electrical power is removed from thecircuitry of apparatus 100 in step 205.

Step 207 determines whether to generate a ranging signal through rangefinder source 105 based on range finder sense timer 113. Step 209determines whether the target is at the desired distance (typically thefocal distance of the lens). If so, illumination hold timer 119 is resetin step 213 so that illumination light source 101 illuminates target103.

If target 103 is not within the desired distance, step 211 determineswhether illumination hold timer 119 has expired. If so, illuminationlight source 101 terminates illuminating target 103.

FIG. 4 shows a flow diagram similar to that in FIG. 3. It is generalizedto accommodate for two brightness levels, as opposed to simply on oroff. The first brightness level is typically full brightness, while thesecond brightness level is dimmer than the first brightness level. Thesecond brightness level may be, for example, 0% to about 90%, about 10%to about 80%, about 20% to about 70%, about 30% to about 60%, about 40%to about 50%, about 10%, about 20%, about 30%, about 40%, about 50%,about 60%, about 70%, about 80%, and/or about 90% of full brightness.The controller includes a power timer and an illumination timer, and itis programmed to cause the light source to emit light at the firstbrightness if the illumination timer is not expired, even if thedistance is outside the range of focus, or not at least substantiallyequal to the focal length; cause the light source to emit light at thesecond brightness if the illumination timer is expired and the distanceis outside the range of focus, or not at least substantially equal tothe focal length; and cause the light source to switch from the secondbrightness to emitting no light if the illumination timer is expired andthe power timer is expired. The illumination timer thus provides abuffer for users who have some difficulty maintaining the target at theappropriate distance; the illumination timer will maintain the lightsource at the first brightness, even if the controller is no longerreceiving a signal indicating that the target is at the focal length,for the duration of the illumination timer. After the illumination timerexpires, the light will be switched to the second brightness, therebyalerting the user to the drift from the focal length. If the target isnot restored to the focal length before the power timer expires, thedevice will be placed in a sleep mode, i.e., no power to theillumination light source.

After the circuitry is activated and the power timer is reset, flowproceeds as follows:

(I) cause the light source to emit light at the second brightness;

(II) determine whether the power timer is expired, and:

-   -   (A) if the power timer is expired, then to cause the light        source to emit no light; or    -   (B) if the power timer is not expired, then to:        -   (1) cause the sensor to measure the distance;        -   (2) determine whether the distance is in the range of focus            or at least substantially equal to the focal length, and:            -   (a) if the distance is in the range of focus or at least                substantially equal to the focal length, then to:            -   (i) reset the power timer and the illumination timer and                cause the light source to emit power at the first                brightness; and            -   (ii) repeat from step (1); or        -   (b) if the distance is not in the range of focus or at least            substantially equal to the focal length, then to determine            whether the illumination timer is expired, and:            -   (i) if the illumination timer is expired, then to:            -   (aa) cause the light source to emit light at the second                brightness; and            -   (bb) repeat from step (II) without first resetting the                power timer; or            -   (ii) if the illumination timer is not expired, then to                repeat from step (1) without first resetting the                illumination timer.

FIG. 5 shows a flow diagram for a simplified scheme that omits theillumination timer. The controller includes a power timer. The secondbrightness is zero brightness, and the controller is programmed to causethe light source to emit light if the power timer is not expired; andcause the light source to emit no light if the power timer is expired.After the circuitry is activated and the power timer is reset, flowproceeds as follows:

(I) cause the light source to emit light at the first brightness;

(II) determine whether the power timer is expired, and:

-   -   (A) if the power timer is expired, then to cause the light        source to emit no light; or    -   (B) if the power timer is not expired, then to:        -   (1) cause the sensor to measure the distance;        -   (2) determine whether the distance is in the range of focus            or at least substantially equal to the focal length, and:            -   (a) if the distance is in the range of focus or at least                substantially equal to the focal length, then to:            -   (i) reset the power timer; and            -   (ii) repeat from step (II); or            -   (b) if the distance is not in the range of focus or at                least substantially equal to the focal length, then to                repeat from step (II) without first resetting the power                timer.

A transition between full illumination and no illumination, or evenbetween full illumination and partial illumination, can be jarring to auser. Consequently, the controller may be programmed to cause the lightsource emission level to transition gradually between the firstbrightness to the second brightness as the distance moves out of therange of focus or changes between at least substantially equal to thefocal length to not at least substantially equal to the focal length.

The various brightness levels may be achieved in a variety of ways. Forexample, as shown in FIG. 4, the power level to the illumination sourcemay be raised or lowered, thereby causing the illumination source toemit higher or lower amounts of light. Alternatively, the light sourcemay include multiple discrete light emitters, of which all are turned onto provide full brightness, and of which fewer than all are turned on toprovide light at dimmer levels.

FIGS. 6-7 show magnifying apparatus 400 in the form of a handheldviewer. The user views target 403 through lens 401. Target 403 isilluminated by illumination sources 405 when the range finder determinesthat target 403 is at the focal distance of lens 401, based on theranging signal transmitted by range finder light source 407 and receivedby range receiver 409.

FIGS. 8-9 show magnifying apparatus 500 in the form of eyeglasses.Apparatus 500 operates in a similar manner as apparatus 400.

As noted previously, a basic premise of focal light magnifiers is thatthe object (target) is illuminated at the focal point of the lens. Inembodiments using illuminating light as the feedback medium, magnifierillumination is triggered by sensors which automatically turn the lighton at the focal point of the lens. Stand magnifier illumination may beconfigured so that the target is at the focal point of the lens whenmaking contact with the stand. By having the object of regard at thefocal point of the lens, light emitted from the lens is parallelrequiring no accommodation, reading lenses, or bifocals. Alternatively,if a user prefers to use the magnifier while wearing reading glasses orbifocals, or while not wearing distance-prescription glasses, themagnifier lens may incorporate an appropriate near-point correction forthe user.

As can be appreciated by one skilled in the art, a computer system withan associated computer-readable medium containing instructions forcontrolling the computer system can be utilized to implement theexemplary embodiments that are disclosed herein. The computer system mayinclude at least one computer such as a microprocessor, digital signalprocessor, and associated peripheral electronic circuitry.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims.

1. A device comprising: a magnifying lens having a fixed, non-adjustablefocal length that defines a focal plane and a range of focus; a lightsource providing visible light directed toward the focal plane; and acontroller programmed to: receive a signal indicative of the distancefrom the device to an object; cause the light source to emit visiblelight at a first brightness if the distance is in the lens's range offocus; and cause the light source to emit visible light at a secondbrightness, dimmer than the first brightness, if the distance is not inthe lens's range of focus.
 2. The device of claim 1, wherein the signalcomprises numerical data that represents the distance.
 3. The device ofclaim 1, wherein the signal comprises numerical data that represents adifference between the focal length and the distance.
 4. The device ofclaim 1, wherein the signal comprises Boolean data indicating whetherthe distance is in the lens's range of focus.
 5. The device of claim 1,wherein the second brightness is about 30% to about 60% of the firstbrightness.
 6. The device of claim 1, wherein the second brightness iszero brightness, and the light source emits no light when the distanceis not in the lens's range of focus.
 7. The device of claim 1, whereinthe controller is programmed to cause the light source emission level totransition gradually between the first brightness to the secondbrightness as the distance moves out of the lens's range of focus. 8.The device of claim 1, further comprising a sensor that measures thedistance from the device to the object and produces the signalindicative of the distance from the device to the object.
 9. The deviceof claim 8, wherein the sensor comprises a transmitter and a receiverthat are arranged on the device to measure the distance bytriangulation.
 10. The device of claim 9, wherein the transmittercomprises a light emitter and the receiver comprises a light detector.11. The device of claim 10, wherein the light emitter emits infraredlight, and the receiver is sensitive to infrared light.
 12. The deviceof claim 8, wherein the sensor comprises an image sensor.
 13. The deviceof claim 12, wherein the sensor comprises a linear image sensor.
 14. Thedevice of claim 8, wherein the sensor is programmed to sample thedistance as it varies over time, and the signal produced is indicativeof time-averaged distance.
 15. The device of claim 8, further comprisinga power timer, and wherein the second brightness is zero brightness, andwherein the controller is programmed to: cause the light source to emitlight if the power timer is not expired; and cause the light source toemit no light if the power timer is expired.
 16. The device of claim 15,wherein the controller is programmed to: (I) cause the light source toemit light at the first brightness; (II) determine whether the powertimer is expired, and: (A) if the power timer is expired, then to causethe light source to emit no light; or (B) if the power timer is notexpired, then to: (1) cause the sensor to measure the distance; (2)determine whether the distance is in the lens's range of focus, and: (a)if the distance is in the lens's range of focus, then to: (i) reset thepower timer; and (ii) repeat from step (II); or (b) if the distance isnot in the lens's range of focus, then to repeat from step (II) withoutfirst resetting the power timer.
 17. The device of claim 8, furthercomprising a power timer and an illumination timer, and wherein thecontroller is programmed to: cause the light source to emit light at thefirst brightness if the illumination timer is not expired, even if thedistance is not in the lens's range of focus; cause the light source toemit light at the second brightness if the illumination timer is expiredand the distance is not in the lens's range of focus; and cause thelight source to switch from the second brightness to emitting no lightif the illumination timer is expired and the power timer is expired. 18.The device of claim 17, wherein the controller is programmed to: (I)cause the light source to emit light at the second brightness; (II)determine whether the power timer is expired, and: (A) if the powertimer is expired, then to cause the light source to emit no light; or(B) if the power timer is not expired, then to: (1) cause the sensor tomeasure the distance; (2) determine whether the distance is in thelens's range of focus, and: (a) if the distance is in the lens's rangeof focus, then to: (i) reset the power timer and the illumination timerand cause the light source to emit power at the first brightness; and(ii) repeat from step (1); or (b) if the distance is not in the lens'srange of focus, then to determine whether the illumination timer isexpired, and: (i) if the illumination timer is expired, then to: (aa)cause the light source to emit light at the second brightness; and (bb)repeat from step (II) without first resetting the power timer; or (ii)if the illumination timer is not expired, then to repeat from step (1)without first resetting the illumination timer.
 19. The device of claim1, wherein: the light source comprises multiple light emitters; allemitters are turned on to provide light at the first brightness; andfewer than all emitters are turned on to provide light at the secondbrightness.
 20. A method comprising: sensing a distance from the deviceof claim 1 to an object; and issuing feedback, perceptible to a user ofthe device, that is indicative of whether the distance is in the lens'srange of focus, the feedback comprising: emitting light at the firstbrightness if the distance is in the lens's range of focus; and emittinglight at the second brightness, dimmer than the first brightness, if thedistance is not in the lens's range of focus.